The process of manufacturing bricks can be divided into at least three distinct stages: (1) manufacture and extrusion of uncured or "green" brick material; (2) cutting of the extruded brick material into green bricks; and (3) drying and firing of the green bricks. These brick formation and handling stages are usually carried out using automated machinery and handling equipment. In conventional prior art brick handling systems, green bricks cut from extruded brick material are positioned on a conveyor system to be delivered to a stacking or loading station where they are stacked on kiln cars for drying and firing.
Green bricks are typically set upon the conveyor in the same direction and orientation. When pairs of these similarly oriented bricks are gripped for stacking, the finished face of one brick in the pair is oriented towards the unfinished back of the other paired brick. Those bricks which have their finished faces oriented towards the interior of a stack of bricks are not exposed to the same drying and firing atmosphere as other bricks. Thus, during the drying and firing process, which often occurs in a reduced pressure environment, this face-to-back orientation of stacked pairs of bricks typically produces inconsistent drying and firing patterns. As a result, undesirable variances in color and color pattern may result on the faces of different bricks.
For purposes of assisting in the subsequent description of brick handling and orientation, a front view of a brick 10 is shown in FIG. 1. The brick 10 is generally of rectangular shape having a longitudinal front face 11 and two transverse side faces 12a and 12b. For ornamental bricks, the brick faces 11, 12a, and 12b may also include ornamental designs or irregular shapes such as that indicated by reference numeral 15. The longitudinal back side of the brick 13 is typically a flat surface. Finally, the brick 10 includes two parallel cut sides 14. Perpendicular to the cut sides 14 and running through the brick 10 may be coring holes 16, honeycomb patterns, or other specialized features.
According to prior art handling methods, a gripping mechanism, such as a vacuum gripper, grips the bricks in pairs to remove them from the conveyor and to stack them for drying and firing. In stacking green bricks, each brick should contact other bricks in the stack on one of the cut faces 14. Otherwise, undesirable marks and irregular patterns may appear on the brick faces. Unfortunately, in order to stack bricks in this fashion, a gripper often must contact a finished face of at least one of the bricks in the pair leaving undesirable marks on the brick face.
This problem is particularly troublesome where ornamental or irregular features are included on the faces of the bricks. In that case, expensive manual handling is necessary to handle such ornamentally designed brick faces. But even in situations where bricks might be gripped on their cut sides, complicated and expensive gripping apparatus are still required to handle bricks which may be cored or honeycombed and to prevent the faces of the bricks from touching.
There is need to provide a brick handling system which can utilize conventional and simple gripping tools and still obtain faultless brick faces of more uniform color and pattern. In addition, it would be desirable if that system could handle irregular or specialized bricks without requiring specialized gripping tools or stacking procedures.